CVE-2025-47917
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.06%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more than one DN).
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 2.06% probability · 80th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- arm/mbed tls
- Source
- cve@mitre.org
References
- https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-7.mdMitigation, Third Party Advisory
- https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/08/msg00013.html
- https://lists.debian.org/debian-lts-announce/2025/08/msg00025.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.